Private clinics are offering testosterone replacement therapy, claiming it will restore sexual desire and treat erectile dysfunction and depression. Prescriptions on the NHS rose 20 per cent from 2012 to 2016.

But Dr Quinton said there was a group of frail men who would benefit from additional testosterone – those with anaemia. A study found one in five were producing zero testosterone but were not being helped.

Dr Quinton told the British Science Festival in Hull: ‘Simultaneously we know men having maybe a minor sexual issue, having a random blood test and given testosterone they really didn’t need at all.’